Data entry interfaces, such as keyboards or keypads, are typically used by a user for entering data into devices, such as mobile devices, e.g., mobile telephones, personal digital assistants, calculators, handheld computers, etc. Keypads for mobile devices are typically small due to the compact nature of mobile devices. As such, the individual keys of a keypad are located rather close together and have a rather small surface area, especially for keypads with 20 or more keys. This can make the keyboard difficult to operate in that a user's finger can depress more than one key at a time.
It is difficult to manufacture keys with such small surface areas in that it is difficult to form indicia on such keys that can still be readable by the user. Moreover, since all of the keys are about the same size and shape it is relatively easy to get the keys mixed up during assembly.